[The impacts of sex hormones on histomorphometric and histological appearances of bone in ovariectomized rats].

OBJECTIVES: To demonstrate the histomorphometric and histological changes of bone 3 weeks after bilateral ovariectomy in rats and to investigate the impacts of 4 different hormone replacement therapies on the bone histomorphometric, histological appearances. METHODS: Bilateral ovariectomies were done on 41 female rats and sham operations on other 9 (sham group) respectively. After 3 weeks, 4 different treatments: i.e. Livial, Gevrine, Premarin, Weinian were initiated separately on each 8 ovariectomized rats for another 3 weeks. The remaining 9 were served as controls (OVX group). All rats were sacrificed either 3 weeks after ovariectomy/sham operation or at the end of hormone therapies. Their femoral bone mineral density (BMD) were measured by dual energy X-ray absorptiometry (DEXA). Specimens of proximal femur were embedded undecacifide for histomorphometric analysis and of distal femoral metaphysics were procured for scanning electron microscope (SEM) and pathologic examinations. RESULTS: (1) Three weeks after OVX, the femoral BMD, mean cortical thickness decreased significantly while the number of osteoclast increased significantly as compared with sham group. The trabecular became thinner and irregular which changed the bone microstructure in three dimension. (2) After treatment of 4 different preparations, the above parameters restored to various extents to the sham operation levels. Among them, there was greater increase of femoral BMD on the Livial and Gevrine group as compared with Premarin and Weinian group (P < 0.05). CONCLUSIONS: Bilateral ovariectomy induced increased osteoclast activity and bone turnover, therefore caused accelerated bone loss. Treatment with combined sex hormones preparation could inhibit bone absorption and stimulate bone formation, especially those containing androgenic activity could increase the BMD.